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Thursday, 23 May 2013

Another Pterosaurs preview, and the soft bits of Tupandactylus

Tupandactylus navigans reclining by sunset, pycnofibres a-glowing.

Holy Toledo, the publication date of Pterosaurs: Natural History, Evolution, Anatomyisnow only weeks away. In exactly one month, preordered copies of the book will be sent out and actual, physical copies of it will be in homes around the world. Forgive me if this sounds indulgent: it's not meant to. It's simply a little mind boggling to think of people paying hard-earned money for the book that, with help from Princeton University Press, I spent over two years writing and illustrating. (Don't forget to add the celebratory Pterosaurs party at the Natural History Museum, London, on September 10th, 2013, to your diary.)

To celebrate this navel-gazing milestone, here's another preview image from the book. It shows the Brazilian tapejarid Tupandactylus navigans at sunset, it's fur-like pycnofibres glowing in the diminishing light. This painting is one of the large paintings that accompanies the start of each chapter and, specifically, it opens Chapter 5: "Soft bits". Each of these large paintings was designed to draw focus to the topic of its chapter. Deciding on the basic composition was easy enough for many chapters, but those focussing on soft-tissue anatomy and osteology proved to be a little bit of a head scratcher. How do you draw specific attention to tissues comprising pterosaur bodies rather than the pterosaur itself? The answer for "Soft bits" at leastseemed to lie in back lighting a pterosaur body so that most of the animal was obscured, save for a halo of illuminated fuzz. Tupandactylus navigans was chosen because it's enormous soft-tissue headcrest (below) contributed to the already unusual outline of a pterosaur body to make a more startling image. "Soft bits" takes on a variety of other soft tissues as well - brains, lungs, guts, skin, wing membranes and so forth - but these seemed harder to bring out without cutting a pterosaur open.

Tupandactylus navigans holotype skull SMNK PAL 2344, showing the crazy headgear sported by some tapejarid species. Remember that this crest is not the largest worn by a tapejarid pterosaur. From Witton (2013).

In other news, today also saw Christopher DiPiazza post an online interview he conducted with me at Jersey Boys Hunt Dinosaurs. The post contains some exclusive artwork, comments on how to get into palaeontology and a frank reply to the question of "should I undertake postgraduate studies in palaeontology?" I'm not the only chap telling people to be cautious about choosing palaeontology as a career at the moment, and seriously recommend that prospective students thinking about joining the palaeo ladder give that choice some serious thought before taking the plunge. Read why here (question 7).

That's all for this week. Next week: pterosaur mummies!

P.S. 'Tupandactylus' navigans? Who he?

Finally, a quick note on the nomenclature used in this post. Readers familiar with tapejarid taxonomy may notice that I'm treating navigans as part of the genus Tupandactylus, whereas it has typically been referred to Tapejara or "Tapejara" by other workers. The nomenclatural history of navigans is a little complicated. It was initially placed in the genus Tapejara (Frey et al. 2003) along with two other species, T. wellnhoferi and imperator. Two teams of authors independently revised the taxonomy of this genus in 2007, with Kellner and Campos (2007) moving imperator to a novel genus, Tupandactylus and Unwin and Martill (2007) creating another new genus, Ingridia, for navigans and imperator, with the latter as the type species. The work of Kellner and Campos was published just before Unwin and Martill and, because they both used imperator as the type taxon of their respective genera, Ingridia must be considered synonymous with Tupandactylus. Kellner and Campos (2007) hinted that navigans was also probably a member of Tupandactylus, but Darren Naish suggested that it may still warrant generic distinction from imperator in a 2008 Tetrapod Zoology article. navigans has been in taxonomic limbo since then, but recent phylogenetic work (e.g. Pinheiro et al. 2011 and my own studies, presented last year at SVPCA 2012 and hopefully being turned into a fully fledged paper when I get the time) has found support for a navigans + imperator clade which bears out earlier suggestions that these species are congeneric. These discussions about generic labels are fairly arbitrary and someone may eventually decide to generically split navigans from tupandactylus but, until then, it seems reasonable to house navigans within the Tupandactylus stable.

16 comments:

That would be Ingridia, not "Ingridius." Note that Darren tried to suggest that this name could be adapted for use of navigans, but of course that's never going to be possible as it was proposed specifically for imperator.

Of course, how silly of me. Post corrected. Being fairly close to the Naish/Martill camp mean I've heard several discussions of names derived from 'Ingrid', and I guess 'Ingridius' was one of them. Another name has been shortlisted as a likely replacement if that ever happens, but I naturally can't say anything about that here.

Don't be too disheartened: there's still a vibrant field in palaeontology, but it's undoubtedly harder than ever to get into. The harsh reality is that young scientists need to be prepared to work like crazy, weather a period of little financial and professional security and perhaps put off things like starting a family for a while if you want to find that dream job somewhere. So it is possible, and I would encourage anyone who is extremely determined to find a job in palaeontology to chase one, but it's only fair that people should know how tough it can be at times.

"I imagine it takes like chicken (the Tupandactylus that is, not the book)."

Could be the book if the comparison is to industrial chicken.

Great art as usual. You should give the chap who does it for you a good pat on the back, but don't wrench your shoulder doing it, eh.

It's tough times for lots of budding scientists. I have a friend who started her PhD in marine biology (at U of Queensland) last September and has been picking up some modest but nice grants for conferences and the like. But, as a foreign student in Australia, money was a big issue and it took her more than two years of on and off paid and volunteer work at the marine biology lab there to get accepted and funded. It helped that her fiancé is a PhD student in the much better funded physics, but was a very tough grind and its not like they're living big now, just not starving so much.

I hugely admire her and folk like you and Darren who've taken what is a hard path indeed.

The pycnofibres on pterosaur fossils are frequently gently curved and randomly orientated, much like preserved fur on fossil mammals, and their density also seems pretty similar. We can't count fibres per square centimetres because their fossils are squashed flat, but we get the same matted, roadkill-like fibrous 'halos' around pterosaur skeletons that we see in fossil mammals and birds. From that, it seems probable that pterosaurs were pretty densely covered in fibres. Put the flexible nature of their individual strands together with their density, and I imagine the result would feel much like mammal fur or downy feathers.

I had the same question (but not the wit to ask it). It might be different even on the same animal. Cats' fur and whiskers are essentially the same but the whiskers are far stiffer. Maybe a pterosaur would have tougher fibres on its back and softer on its tummy, ideal for rubbing!

Great work as always! Really looking forward to the book. I have it pre-ordered.

I was curious as to your thought process behind how you depicted the soft tissue crest in particular. On a lot of heavily-backlit illustrations, soft bits like wing membranes tend to be depicted with a translucent "subsurface scattering" type of effect - much like what you have with his glorious pycnofiber mane. I noticed that you depicted the crest fairly solid without any light coming through, and was wondering if there is any support one way or another for how to tell if a soft bit such as a crest or wing membrane was likely to be translucent or not?

Sorry for the delay in replying. Good question about soft-tissue translucency. The short answer is the we probably don't really know based on fossils alone, and have to rely on modern analogues. Here, I've imagined the crest being fairly tough and rigid - there's not much bony support for it, really - and thus opaque in even direct sunlight. The wing membranes may have been more translucent than shown here as they are fairly thin (although not of uniform thickness across the wing), but I think I can get away with it in this poorly-lit, shady image.

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Who is this 'Mark Witton' chap?

Dr Mark Witton is a palaeontologist and palaeoartist, affiliated with the University of Portsmouth, UK. My technical research is focused on pterosaurs - Mesozoic flying reptiles - but my artwork has introduced me to a wide array of different fossil animals that are just as interesting. I work as a freelance author, consultant and artist: check out my work at MarkWitton.com, follow me on Twitter @MarkWitton, and browse my books here. Contact me at wittonprints[at]gmail.com. Due to volume of email I can't always reply to messages, but I do my best.